Carbon nanotube nanoelectrode arrays

Abstract

The present invention relates to microelectode arrays (MEAs), and more particularly to carbon nanotube nanoelectrode arrays (CNT-NEAs) for chemical and biological sensing, and methods of use. A nanoelectrode array includes a carbon nanotube material comprising an array of substantially linear carbon nanotubes each having a proximal end and a distal end, the proximal end of the carbon nanotubes are attached to a catalyst substrate material so as to form the array with a pre-determined site density, wherein the carbon nanotubes are aligned with respect to one another within the array; an electrically insulating layer on the surface of the carbon nanotube material, whereby the distal end of the carbon nanotubes extend beyond the electrically insulating layer; a second adhesive electrically insulating layer on the surface of the electrically insulating layer, whereby the distal end of the carbon nanotubes extend beyond the second adhesive electrically insulating layer; and a metal wire attached to the catalyst substrate material.

1. A nanoelectrode array comprising:
 a carbon nanotube material comprising an array of substantially linear carbon nanotubes each having a proximal end and a distal end, the proximal end of the carbon nanotubes are attached to a catalyst substrate material to form the array with a pre-determined site density, wherein the carbon nanotubes are aligned with respect to one another within the array; 
 an electrically insulating layer on the surface of the carbon nanotube material, whereby the distal end of the carbon nanotubes extend beyond the electrically insulating layer; 
 a second adhesive electrically insulating layer on the surface of the electrically insulating layer, whereby the distal end of the carbon nanotubes extend beyond the second adhesive electrically insulating layer; and 
 a metal wire attached to the catalyst substrate material. 
 
     
     
       2. The nanoelectrode array of  claim 1 , wherein the electrically insulating layer comprises a metal oxide. 
     
     
       3. The nanoelectrode array of  claim 2 , wherein the metal oxide is silicon dioxide (SiO 2 ). 
     
     
       4. The nanoelectrode array of  claim 1 , wherein the second adhesive electrically insulating layer comprises a polished exterior surface. 
     
     
       5. The nanoelectrode array of  claim 1 , wherein the second adhesive electrically insulating layer comprises an epoxy-phenolic adhesive. 
     
     
       6. The nanoelectrode array of  claim 1 , wherein the array of substantially linear carbon nanotubes provide an electrochemical sensing device for the detection of a metal ion. 
     
     
       7. The nanoelectrode array of  claim 6 , wherein the metal ion is selected from the group consisting of lead, arsenic, copper, cadmium, zinc, chromium, mercury, uranium, bismuth, thallium, tin, antimony, tellurium, iodine, selenium, gold, silver, cobalt, nickel, thorium and plutonium. 
     
     
       8. The nanoelectrode array of  claim 1 , wherein the array of substantially linear carbon nanotubes provides an electrochemical sensing device for the detection of a drug. 
     
     
       9. The nanoelectrode array of  claim 8 , wherein the drug is selected from the group consisting of 4-acetamidophenol, carbonhydrates, insulin, cystein, hemocysteine, sulfide, phenolic compounds, choloramphenicol, myoglobin, 3,4-dihydroxyphenyacetic acid, hypoxanthine, ascorbic acid, uric acid, catechol, tryptophan, nitrite, L-dopa, dopamine, norepinephrine, and nitric oxide. 
     
     
       10. A nanoelectrode array for the selective detection of glucose comprising:
 a carbon nanotube material comprising an array of substantially linear carbon nanotubes each having a proximal end and a distal end, the proximal end attached to a catalyst substrate material to form the array with a pre-determined site density, and a carboxylic acid group functionalized to the distal end of the carbon nanotubes, wherein the carbon nanotubes are aligned with respect to one another within the array; 
 an electrically insulating layer on the surface of the carbon nanotube material, whereby the distal end of the carbon nanotubes extend beyond the electrically insulating layer; 
 a second adhesive electrically insulating layer on the surface of the electrically insulating layer, whereby the distal end of the carbon nanotubes extend beyond the second adhesive electrically insulating layer; and 
 a metal wire attached to the catalyst substrate material, 
 wherein the carboxylic acid group attached to the distal end of the carbon nanotubes is coupled to a glucose oxidase enzyme for the selective detection of glucose. 
 
     
     
       11. The nanoelectrode array of  claim 10 , wherein the catalyst substrate material comprises a non-metallic material having deposited thereupon a layer of a metallic material, and a plurality of catalytic transition metal microparticles deposited upon the metallic material with pre-determined densities. 
     
     
       12. The nano electrode array of  claim 11 , wherein the non-metallic material is a silicon wafer. 
     
     
       13. The nanoelectrode array of  claim 11 , wherein the metallic material is chromium (Cr). 
     
     
       14. The nanoelectrode array of  claim 11 , wherein the catalytic transition metal microparticles comprise nickel (Ni). 
     
     
       15. The nanoelectrode array of  claim 10 , with pre-determined densities of up to 1×10 12  cm −2 . 
     
     
       16. The nanoelectrode array of  claim 10 , wherein the electrically insulating layer comprises a metal oxide. 
     
     
       17. A nanoelectrode array for detecting a metal ion in a solution comprising:
 an array of vertically aligned carbon nanotubes having a pre-determined site density, wherein each carbon nanotube in the array has a proximal end and a distal end and wherein the proximal end of each carbon nanotube is attached to a metallic coating on a non-metallic substrate; 
 an electrically insulating layer on a surface of the array of vertically aligned carbon nanotubes, whereby the electrically insulating layer insulates the metallic coating on the non-metallic substrate; 
 a second adhesive electrically insulating layer surrounding the electrically insulating layer, whereby the second adhesive electrically insulating layer insulates the metallic coating on the non-metallic substrate and supports the array of vertically aligned carbon nanotubes; and an electrical connection attached to the substrate, 
 wherein the distal end of each of the carbon nanotubes is exposed to electrochemically sense the metal ion in the solution. 
 
     
     
       18. The nanoelectrode array of  claim 17  wherein each of the carbon nanotubes has a diameter ranging from about 50 nm to about 80 nm. 
     
     
       19. A nanoelectrode array for generating an amperometric response to at least one drug in a solution comprising:
 an array of vertically aligned carbon nanotubes having a pre-determined site density, wherein each carbon nanotube in the array has a proximal end and a distal functionalized end and wherein the proximal end of each carbon nanotube engages to a metallic coating on a non-metallic substrate, and wherein the distal functionalized end of each carbon nanotube is coupled to a glucose oxidase; 
 an electrically insulating layer on a surface of the array of vertically aligned carbon nanotubes, whereby the electrically insulating layer insulates the metallic coating on the non-metallic substrate; 
 a second adhesive electrically insulating layer surrounding the electrically insulating layer, whereby the second adhesive electrically insulating layer insulates the metallic coating on the non-metallic substrate and supports the array of vertically aligned carbon nanotubes; and 
 an electrical connection attached to the substrate, 
 wherein the glucose oxidase is capable of interacting with the at least one drug in the solution to generate an amperometric response. 
 
     
     
       20. The nanoelectrode array of  claim 19  wherein the at least one drug is selected from the group consisting of 4-acetamidophenol, carbonhydrates, glucose, insulin, cystein, hemocysteine, sulfide, phenolic compounds, choloramphenicol, myoglobin, 3,4-dihydroxyphenyacetic acid, hypoxanthine, ascorbic acid, uric acid, catechol, tryptophan, nitrite, L-dopa, dopamine, norepinephrine, and nitric oxide.